1. Field of the Invention
The present invention relates to a multi-piece solid golf ball having a core composed of a center core encased by an envelope layer and, formed over the core, an intermediate layer and a cover.
2. Prior Art
To increase the distance traveled by a golf ball and also improve the feel of the ball when played, innovations have hitherto been made which involve providing the golf ball with a multilayer structure. Various golf balls with multilayer structures of three or more layers have subsequently been proposed in order to achieve a lower spin rate and a higher initial velocity and to further improve the feel at impact.
Today, golf balls having a somewhat soft cover, an intermediate layer formed of an ionomer material that is relatively hard compared with the cover, and a solid core with a one-layer or two-layer-construction that is formed of a rubber material are widely used by professional golfers and skilled amateur golfers as golf balls endowed with excellent flight performance and controllability. Such balls, owing to the somewhat soft cover, exhibit a high controllability in the short game. By combining such a cover with, on the inside thereof, a layer made of a hard, high-resilience ionomer material, the ball suppresses excessive spin on full shots with a driver and also achieves a high rebound.
Such golf balls have been disclosed in, for example, U.S. Pat. Nos. 6,071,201, 6,254,495, 6,271,296, 6,394,912, 6,431,998, 6,605,009, 6,688,991, 6,756,436, 6,824,477, 6,894,098, 6,939,907, 6,962,539, 6,988,962, 7,041,009, 7,125,348, 7,157,512, 7,230,045, 7,285,059, 7,641,571 and 7,652,086, JP-A 2012-40376, JP-A 2012-45382 and U.S. Pat. No. 7,648,427.
Hence, there is a strong demand among professional golfers and skilled amateurs for golf balls which are capable of exhibiting a level of performance in keeping with one's own skill level. Accordingly, developing golf balls having a flight performance, controllability, feel at impact and durability that are capable of satisfying a greater number of golfers, is important for expanding the golfer base.
In addition, U.S. Published Patent Application Nos. 2014/0018191 and 2014/0100059, JP-A 2013-230361, JP-A 2013-230362, JP-A 2013-230363, JP-A 2011-217857 and JP-A 2011-136021 describe various art specifying the core cross-sectional hardness profile in multi-piece solid golf balls. However, there has existed a desire for novel art which optimizes overall such parameters as the core hardness and the thickness, hardness and material of the intermediate layer so as to further improve the performance of these golf balls.
It is therefore an object of this invention to provide a multi-piece solid golf ball which has an increased distance and a soft feel at impact, and is also able to prevent a decline in the durability to cracking.